1. Field of the Invention
The present invention relates to a spread illuminating apparatus for illuminating displays, such as signboards or various kinds of reflection type display apparatus, in particular liquid crystal displays.
2. Description of Related Art
Currently, due to a low power consumption, relative compactness and light weight, the demand for liquid crystal display apparatuses as displays for computers has increased. As opposed to a light emitting type element, such as a picture tube, the liquid crystal element of the liquid crystal display does not emit light itself, and therefore, the liquid crystal display needs to be illuminated in order to view a picture.
In order to illuminate the liquid crystal display while maintaining compactness, a thin plate-like side light type (light conductive member type) spread illuminating apparatus has been often used. An example of such a side light type of spread illuminating apparatus is shown in FIGS. 6 to 8.
FIG. 6 shows a spread illuminating apparatus 1 that includes a longitudinal light source 4 disposed close to one end face 3 of a transparent substrate 2 made of a light permeable material. The transparent substrate 2 is formed to have a wedge-shaped cross section in which the thickness of the transparent substrate 2 tapers from thick to thin as the distance from the one end face 3 is increased.
The light source 4 is formed in general with a long plate-like light conductive member 5 made of a light permeable material and disposed along and close to the one end face 3 of the transparent substrate 2 and a spot-like light source 6 disposed facing one end 5a of the light conductive member 5, and a reflection plate 7 is disposed on and facing the other end 5b of the light conductive member 5.
Additionally, a U-shaped light reflection member 9 is provided in such a manner as to partially cover the longitudinal circumferences of the longitudinal light conductive member 5. As shown in FIG. 6, the light reflection member 9 covers only a second face 5d, a third face 5e, and a fourth face 5f of the light conductive member 5. As shown in FIG. 8, the light reflection member 9 also covers a proximal portion 8 of the transparent substrate 2. Also, as shown in FIG. 8, between both facing portions 9a and 9b of the light reflection member 9 and the proximal portion 8 of the transparent substrate 2, double-faced tape 10 is interposed and adapted to fix the light reflection member 9 to the proximal portion 8.
On an upper surface 11a of the transparent substrate 2, a light reflection pattern 12 is formed. The light reflection pattern 12 is adapted to cause every portion of the transparent substrate 2 to have an approximately uniform brightness, regardless of the distance from the light conductive member 5.
In the conventional art indicated in FIGS. 6 to 8, the light reflection member 9 is fixed to the transparent substrate 2 by using the double-faced tape 10, and there have been the following problems often occurring.
First, at the time of fixing the light reflection member 9 to the transparent substrate 2, a process consuming time for adhering the light reflection member 9 to the transparent substrate 2 using the double-faced tape 10 is required, and to that extent, productivity is lowered.
Further, the apparatus as a whole becomes thicker due to the double-faced tape 10 interposed between the light reflection member 9 and the transparent substrate 2, as shown in FIG. 8. Additionally, because the double-faced tape 10 is applied on the proximal portion 8, where light enters the transparent substrate 2, nonuniformity in rightness at the time of viewing can be generated due to irregularity in applying the double-faced tape 10.
The present invention has been made in the light of the above circumstance and in order to provide a compact spread illuminating apparatus which can improve productivity and also prevent any nonuniformity of brightness in the illumination at the time of viewing.
According to a first aspect of the present invention, a spread illuminating apparatus is provided in which a bar-like light source is disposed close to an end face of a transparent substrate made of a light permeable material, wherein a frame comprising a light reflection member or having a light reflecting function, which is rigid and configured as having an approximately C-shaped or U-shaped cross-section, is disposed in such a manner that it covers the light source and extends as far as a proximal portion of the transparent substrate and that at least one of two facing plates thereof is provided with resilience working toward an opposing facing plate.
According to a second aspect of the present invention, a spread illuminating apparatus is provided in which a longitudinal light source is disposed close to an end face of a transparent substrate made of a light permeable material, wherein the light source is formed with a long plate-like light conductive member made of a light permeable material disposed along and close to at least one end face of the transparent substrate and a spot-like light source disposed close to one or both end faces of the light conductive member, and a frame comprising a light reflection member or having a light reflecting function, that is configured as having an approximately C-shaped or U-shaped cross section, is disposed in such a manner that it covers longitudinal surfaces of the light conductive member except a surface facing the transparent substrate and extends as far as a proximal portion of the transparent substrate, and that at least one of two facing plates hereof is provided with resilience working toward an opposing facing plate.
According to a third aspect of the present invention, resilience of the frame is obtained by pre-bending end portions of the facing plates of the frame toward each other.
According to a fourth aspect of the present invention, the pre-bending is carried out at a proximal portion of the facing plates.
According to a fifth aspect of the present invention, the pre-bending is carried out between the end portion and the proximal portion of the facing plates.
According to a sixth aspect of the present invention, the transparent substrate is tapered away from the one end to form a wedge-shape.
According to a seventh aspect of the present invention, the resilience of the frame is obtained by a projection formed on one or both of the facing plates in such a manner that the projection extends toward the opposing facing plate.
According to an eighth aspect of the present invention, the projection is formed as a cut-raised piece to be worked by a press working, and the projection is bent to be in parallel with the facing plate.